Is spinlock required for every interrupt handler?

Question

In Chapter 5 of ULK the author states as follows:

"...each interrupt handler is serialized with respect to itself-that is, it cannot execute more than one concurrently. Thus, accessing the data struct does not require synchronization primitives"

I don't quite understand why interrupt handlers is "serialized" on modern CPUs with multiple cores. I'm thinking it could be possible that a same ISR can be run on different cores simultaneously, right? If that's the case, if you don't use spinlock to protect your data it can come to a race condition.

So my question is, on a modern system with multi-cpus, for every interrupt handler you are going to write that will read & write some data, is spinlock always needed?

Answer 1

While executing interrupt handlers, the kernel explicitly disables that particular interrupt line at the interrupt controller, so one interrupt handler cannot be executed more than once concurrently. (The handlers of other interrupts can run concurrently, though.)